Video: Could a nuclear meltdown happen in U.S.?

Closed captioning of: Could a nuclear meltdown happen in U.S.?

>> reporter: good morning. nuclear regulators say u.s.
nuclear power plants
are built to with stand significant earthquakes and tsunamis and that current safeguards are adequate to protect the public. but the japanese officials would have said the seem thing a week ago. some scientists warn what's happening in
japan
could happen here. this was not supposed to happen. a number of japanese reactors out of control, the threat of a nuclearle me meltdown. in the u.s. there are 104 nuclear
power plants
which provide 20% of electricity here. edward limon says this shows
safety standards
should be raised across the board. could what happened in
japan
happen here?

>>yes. i'm afraid it could. unless we learn the lessons of this accident it's only a matter of time.

>> reporter: issue one, earthquakes. some
nuclear plants
are located in or near areas of seismic risk. the greatest hazards, the areas in red. u.s.
nuclear plants
are required to be able to with stand the worst earthquake expected in their area. plus a margin of safety. two california plants are in earthquake-prone areas,
diablo canyon
built to with stand a 7.5 magnitude quake and, designed to with stand a 7.0,
san onofre
.
japan
's was a 9.0.
richard lester
of m.i.t.

>>we need to consider the possibility of greater magnitude earthquakes than we had previously considered.

>> reporter: issue two, plant design. this is a design of the reactor in
japan
?

>>that's correct.

>> reporter: there are 31 plants in the u.s. similar to those in trouble in
japan
, designed by
general electric
which is a part owner of
nbc universal
. one,
oyster creek
in new jersey, is the oldest
nuclear plant
in the country, about 50 miles from new
york city
. issue three,
backup power
systems. experts say the japanese reactors basically got into trouble because they lost electricity and
backup power
systems failed, too, leaving them struggling to cool the
reactor core
. marvin fertell of the
energy institute
says thanks to improvements since 9/11, u.s. plants have more ability to cope if power is lost.

>>we would be able to handle the situation much easier than the japanese are facing now.

>> reporter: could what happened in
japan
happen here?

>>could we have an event that -- we think -- i would say it's highly improbable it could happen here. if it did, i think we would handle it quite well here.

>> reporter: democratic congressman
ed markey
called for a moratorium on building new reactors in earthquake-prone areas of this country until a sweeping safety review is conducted of exactly what went wrong in
japan
.

>>lisa myers
for us in washington, thank you very much. it's 34 after the hour.

The pipe that released the gas is typically filled with water and hydrogen, which are used to cool the generator, The Olympian reported. Paoli told the newspaper the pipe had been closed and cleaned out — "or so they thought" — at the time of the incident.

An "unusual event" describes a condition that could potentially compromise normal safety levels, the least serious of four NRC emergency classifications.